Franklin roberts



. F. ROBERTS. TANK FOR HOLDING GOMPRESSED AIR.

No. 105,128. Patented July 5, 1870.

waited" States we emit.

FRANKLIN ROBERTS, OF NEW ORLEANS, LOUISIANA, ASSI GNOR TO NEW ORLEANS PNEUMATIC PROPELLING COMPANY, OF SAME PLACE.

Letters Patent No. 105,128, dated July 5, 1870.

IMPROVEMENT IN-TANKS m: HOLDING- COMPRESSED AIR.

The Schedule referred to in these Letters Patent and making part of the same.

I, FRANKLIN ROBERTS, of the city of New Orleans and State of Louisiana, have invented a certain Im provement in Tanks for Holding Compressed Atmospheric Air, when the same is used as the'niotive power for propelling street-railroad cars, of which the following is a specification.

My invention relates especially to the construction of paper tanks; and o It has for its object- First, to prevent the saturation of the same with the gutter or moisture that enters the tank either dird dtly from the compressing-pump or by reason of the condensation resulting from the compression of a large body of air into a small space.

Secondly, to strengthen the tankby means of an outside wrapping of the cord, technically known as marline, which, at the same time, prevents the tank from flying to pieces in case of an explosion, and hence interposes an eifectual guard against injury to any person or thing should an explosion ever take place.

Thirdly, to construct, put in, and secure in their places, the metallic heads which are necessary in the use of paper tanks, as made by me, in such manner that, while no amount of pressure' from within can drive them out, the greater that pressure the tighter will be the joints around them; and

Finally, the adaptation of outside bands to the ends of I the tanks, and the keeping of such bands in place by means of an outside yoke at each end of the tank, and longitudinal rods outside the tank extending from one nd thereof to the other.

B t invention will be more easily and quickly understood if described by direct reference to the ac- .companying drawing, whereon- Figure 1 is an end View of a tank with its heads in place, as when ready to be put on a car; and

Figure 2 a longitudinal section, through line a b of fig. 1, of a part of a tank and one head thereof.

In the formation of the shell A of the tank, a mandrel or former is employed in order to cause said shell to assume the shape shown on the drawing; that.

is to say, to taper for a short space at each end inwardly in a straight line from the points at which a areduction of the diameter commences to the said ends.

The black line a, which marks the interior surface of the shell of the tank, represents a wrapping of sheet India rubber, which is put tightly around the former before the paper is put on, in such a mannor that one edge will overlap the other with the view to cover the joint which would otherwise obtain.

This interior wrapping of sheet rubber efi ectuallyprevents the saturation of the enveloping folds of paper by the water or moisture which may find 1ts way into the tank in its actual use, and hence fulfils the purpose of preserving the normal strength of the paper as long. as the tank may be used.

The elastic properties of the sheet of rubber will prevent the formation of any wrinkles or puckers on the tapering ends of the former, and hence secure as much smoothness of surface there as anywhere else in said sheet.

Over the India rubber exterior lining of the tank comes the wrapping of strong paper, well saturated with glue or varnish, the same being wound around spirally, and so as to break the joints everywhere, as one fold after another is put around, until from thirty to sixty folds encircle the rubber according to the thickness and strength of the paper, and the tension of air it is designed towithstand.

Outside the paper I wind on one thickness or layer of the tarred, slightly-twisted cord, technically called mar-line, as closely as it can be wrapped, and as. tightly as the strength of the marline will permit.

This wrapping of marline addsgreat strength to the shell without greatly increasing its weight, and, in case of explosion, prevents the tank from flying into fragments. The former, which is so constructed as to be susc'eptible of being reduced in diameter by the withdrawal, endwise, of certain of its parts, is now taken out, leaving the shell of the tank at each of its ends of tapering form, as shown at 1 2, fig. 2.

The ends of the tanks are closed with heads, 13, which, upon their periphery or rim, have an inclination or bevel from their inner to their outer edges, which corresponds precisely with the inclination or taper of the end of the tanks, as clearly shown at fig. 2.

The diameter of the heads B should be such that the shell at the ends of the tank shall extend alittle space beyond them when first put in, in order to allow for their gradual movement outwardly under the influence of the enormous pressure which the compressed air developes when the tension thereof approaches three hundred pounds to the square inch,which said tension experience has demonstrated to be requisite in order to make the pneumatic engine an effective motor for the propulsion of street-cars the necessarydlstance, without replenishing before getting back to the gener al reservoir.

In order to combine lightness with strength in the heads B, the plate 0 (see fig. 1) is made thin, but is strengthened by radiating ribs, 0, projecting above the surface of the plate, as shown both on the inside and outside thereof, the ribs on the inside being placed exactly between those on the outside, so as to make the reinforcement they impart as extended'as possible.

Outside the inclined or tapering ends of the tanks, bands, D, encircle the same, as shown at both figures. These bands, on their internal snrmces, are inclined or beveled in reverse direction thereto, and to the heads B, so as to conform precisely to the taper of the ends, as shown at fig. 2. In consequence of this formation of the bands, the pressure from within the tanks against the heads'does not tend to throw the bands oil, but, on the contrary, to fix them themore firmly in their places, because the shell of the tank, iuterposing between the heads and the bands, no movement on the part of the heads can have any efi'ect on the hands, except in the plane of the plate of which the head is composed, which makes the bands gripe the more tightly instead of throwing them ofi.

The bands D may have three or more lugs, E, projecting beyond their outer surfaces, in which holes are made to receive the ends of small bars of iron, if desired, that extend from one head to another, and, by means of screw taps or keys, hold the two heads in place. But, in addition to this, the heads 13 are provided with a central screw-bolt, F, in order to hold in position a cross-bar 0r yoke, G, which, taking against the outer edge of the band, at once affords' a means for preventing the same from slipping ofi', and of tightening the head B. I have found, in fact, that this yoke is usually quite suflicient to hold the bands in place without the aid of the rods to which I have just referred, when the tension was even more than three hundred pounds to the square inch, which is the maximum in the propulsion of city cars by C. N.

XVaileys pneumatic engine.

The heads B are insertedinto the tanks edgewise, by a gentle compression or flattening of the ends of the latter, so as to make them assume an elliptical form,

and then turned into proper position.

They can at any time be taken out in the same way, if, for any cause, it be necessary to withdraw them, as, for example, to empty any water that may have got into the tank, or to dry the interior thereof, 85c.

Myinvention is an improvement on the paper reservoir for compressed air as patented by Charles W.

Wailey, September 1, 1868, which experience has proved to be imperfect, while mine, on .the contrary, fulfils every condition as to strength, durability, lightness, and cheapness, which is required to make the pneumatic engine a perfect motor for the propulsion pose set forth.

' FRANKLIN ROBERTS.

Witnesses:

RUFUS R. RHODES, Emm H. LE Y. 

